<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>圆形</title>
    <style>

        .circle{
            height: 200px;
            width: 200px;
            background-color: lightsteelblue;
            border-radius: 50%;

        }
        .circle:hover{
            transition: box-shadow 2s linear 0ms;

            box-shadow: inset 20px 20px 10px 5px black;

        }
    </style>


</head>
<body>


    <div class="circle">

    </div>




</body>
</html>